Permanent mold with sand dome



June 17, 1958 c. F. STROM 2,83,816

I PERMANENT MOLD WITH SAND DOME Filed Sept. 14, 1955 2 Sheets-Sheet 1 22 J8 .21 M 1.9 a! a2 J 7 H g; x aa i 2,83&,816

June 17, 1958 c. F. STROM PERMANENT MOLD WITH SAND DOME 2 Sheets-Sheet 2 Filed Sept. 14, 1955 z f g iggyoza.

By as a United States Pate PERMANENT MOLD WITH SAND DOME Charles F. Strom, Glen Ellyn, Ill., assignor to Grillin Wheel Company, Chicago, Ill., a corporation of Delaware This invention relates to molds suitable for use in forming metal castings and more particularly to molds adapted for use with pressure casting apparatus in which molten metal is forced upwardly under pressure through an ingate and thence into thebottom of a mold cavity provided with a stopper movable downwardly into seated engagement with the ingate after the cavity has been filled with molten metal.

Briefly, the present invention contemplates the provision of a permanent mold structure particularly adapted for use in casting steel railway car wheels or the like in which the casting may comprise, for example, hubl and rim portions of relatively heavy cross section interconnected by a web ofrelatively thin cross section. To insure the production of steel castings of suitable quality, it is essential that the mold be provided with vents to allow the free escape of mold atmosphere from the casting cavity, whereby a better flow of metal into the cavity is accomplished. It is, therefore, an object of the invention to provide a mold structure having a hub portion ofthe mold cavity, said passage having a sand head through which mold atmosphere may be vented.

Another object of the invention resides in the provision of a permanent mold having baked therein a porous sand dome, or head, through which mold atmosphere may be vented from a casting cavity, the porous sand dome also acting to decrease the possibility of a vacuum condition within the mold cavity after the stopper is moved to its closed position at the completion of the pouring operation.

Another object of the invention resides in the provision of a method and apparatus for baking resin bonded sand cores within the riser passageways of a permanent mold structure. By providing the permanent mold with a resin bonded sand hub riser head, it is possible that a reducing atmosphere may be created in the mold during the pouring operation, due to the burning of the resin bonded sand. Due to the insulating eifect of a sand hub riser head, the molten metal riser therein is maintained in a molten condition for a suflicient length of time to feed metal downwardly into the hub portion of the mold cavity after the completion of the pouring operation.

' Another object resides in the provision of a permanent mold structure having a hub riser cavity provided with a sand head which is spaced from the hub cavity by a cylindrical graphite wall which serves as a freeze-off to permit quick-pick up of cast wheels without disengaging the stopper stem from the wheel.

Another object of the invention resides in the provision of a mold embodying means including a sand dome for positively guiding a plug or stopper into seated engagement with an ingate to prevent a reverse flow of metal downwardly from the casing cavity at the completion of the pouring operation.

Another object of the invention resides in the provision of a permanent mold structure having an annular casting cavity provided with hub and rim riser passage- Patented June 17,, 1958 ways provided with resin bonded porous sand cores.

Another object resides in the provision of a mold structure embodying a guide member spaced above and coacting with the sand dome to slidably receive and positively guide a stopper rod.

Another object of the invention resides in the provision of a mold structure in which the stopper rod is guided for vertical movement by means comprising a metallic washer imbedded in the sand dome and a fiberboard tube mounted on the guide member, the metallic washer also serving to prevent metal flow upwardly between the stopper rod and the sand dome.

Another object of the invention resides in the provision of a permanent mold structure in which only resin bonded sand, metal and graphite are in contact with the molten metal within the mold cavity.

The invention embodies other novel features, details of construction and arrangement of parts which are herinafter set forth in the specification and claims and illustrated in the accompanying drawings, wherein:

Figure 1 is a vertical section view illustrating a permanent mold structure embodying features of the invention;

Figure 2 is a vertical sectional view illustrating the method and apparatus employed for forming and baking resin bonded sand riser walls or heads on the cope of a permanent mold structure.

Referring now to the drawings for a better understanding of the invention and more particularly to Figure l therein, the mold is shown as comprising a graphite cope 2 and a graphite drag 3, defining therebetween a casting cavity 4 suitable for casting steel railway car wheels or the like having concentric hub and rim portions of relative thick section interconnected by a web of relatively thin section.

The drag 3 is provided with an ingate 6 through which molten metal is forced upwardly under pressure into the bottom of the hub portion of the casting cavity 4, the ingate being coaxial with the cavity and formed at its upper end with a frusto-conical seat 6' for engagement by a stopper 7 having a metallic tubular stem 8 projecting upwardly through the cope 2.

The cope 2 is formed with coaxial bores 9 and 11 merging with an annular downwardly facing shoulder 12 to receive a porous resin bonded sand head 13 having a concave lower surface 14 to define with the bore 11 a hub riser cavity 16. It will be noted that the lower end of the head is spaced upwardly from the lower end of the bore 11 to leave a cylindrical graphite wall below the head to serve as a freeze-off to permit quick pick-up of cast wheels without disengaging the stopper stem 8 from the wheels. It will also be noted that the annular shoulder 12 serves to prevent blow-out of the head 13 during the casting operation. A preferably metallic washer 17 is embedded within the lower end of the head, the washer and head having coaxial openings to snugly slidably receive the stopper stem-1 8.

The upper end of the cope 2 is bored at 18 to snugly receive a metallic guide spider 19 having concentric rings 21 and 22 interconnected by radial ribs 23. The inner ring 22 is formed with a bore 24 terminating at its lower end at a shoulder 26, the bore being provided to snugly receive the lower end of a fiberboard tube 27. The stopper stem 8 extends upwardly through the tube 27 and is detachably engaged again'st movement relative thereto by means of a staple 28 which serves to clamp diametrically opposed sides of the tube against the stem when the stopper 7 is to be held in its raised open position. The upper end of the stopper stem is formed with apertures 29 to receive a hook of a lifting device employed to raise a casting from the mold.

The graphite cope 2 is formed with a plurality of circumferentially spaced riser bores 31' extending axially therethrough and disposed inwardly radially from the rim section of the casting cavity 4. Each bore 31 is provided with .a generally cup-shaped liner 32 comprising a baked resin bonded sand, the liner having a side .wall 33 of gradually increasing thickness toward its base 34 which is formed with a sprue 36 leading into the casting cavity 4. The sand liners 32 thus form individual riser chambers 37 communicating with the casting cavity at circumferentially spaced positions.

Figure 2 in the drawings illustrates the method and apparatus employed in forming and baking the sand liners 32 and sand head 13 on the graphite cope 2. The appararatus is shown as comprising a carrier 41 centrally supported upon the upper end of a piston 42 mounted in a cylinder 43 which, in turn, is supported upon a base 44.

A head baking unit 46, mounted on the carrier 41, comprises a metallic plug 47 having a base 48 and a stem 49 integral and coaxial therewith. The base 48 is adapted to be snugly slidably engaged within the bore 11 for a portion of its length and formed with a seat 50 to support the washer 17 which is preferably of larger diameter than the seat, whereby the marginal portion of the washer will be imbedded within the sand head. An electrical heating element 51 is provided to heat the base 48 and stem 49 to bake the resin bonded sand to form the head 13.

The carrier 41 supports a plurality of metallic heating plates 52 adapted to close the lower ends of their respective riser bores 31 and to coact with tapered plugs 53 to form and bake the cup-shaped liners 32. Each heating plate 52 is provided with a sprue plug 54 and an electrical heating element 56 adapted to bake the resin bond sand forming the liners 32. The heating elements 56 and 51 are adapted to be connected to a suitable supply of current under the control of one or more thermostats.

In the use of the mold with pressure casting apparatus, molten metal is forced upwardly through the ingate 6 to fill the casting cavity 4; after which, the stopper 7 is manually moved downwardly into engagement against the seat 6. After solidification of the metal casting, the cope 2 is removed from the drag 3 and the casting is removed from the latter by means of a lifting device adapted to be connected to the stopper stem 8 by means of a hook engaged in the stem apertures 29.

I claim:

1. In a mold, the combination of a cope and drag defining a casting cavity, an opening through'said cope communicating with said cavity, a porous dome in said opening spaced from the bottom of said opening, a guide ring recessed in the bottom of said dome, an opening through the dome aligned with said ring, a gate through the drag, a plunger extending through said opening and ring into said cavity, and a seat on said plunger engageable with the drag to close said gate.

2. In a mold, the combination of a cope and drag defining a casting cavity, an opening through said cope communicating with said cavity, a porous dome in said openingspaced from the bottom of said opening, a guide ring recessed in the bottom of said dome, an opening through the dome aligned with said ring, a gate through the drag, a plunger extending through said opening and ring into said cavity, and a seat on said plunger engageable with the drag to close said gate, and a downwardly facing seat on said cope engaged with the dome to retain the latter in said opening as molten metal from said gate contacts the dome.

3. In a mold, the combination of a cope and drag defining a casting cavity, said cope having an opening communicating with said cavity, a porous head mounted in and spaced from the bottom of said opening and formed with an axial stopper stem aperture, said drag having a gate formed with a seat coaxial with said aperture, a stopper engageable with said seat to close said gate and having a stem slidablymounted in said stem aperture,

4. In a mold, the combination of a cope and drag defining a casting cavity, said cope having an opening communicating with said cavity, a porous head mounted in spaced from the bottom of said opening and formed with an axial stopper stem aperture, said drag having a gate formed with a seat coaxial with said aperture, a stopper engageable with said seat to close said gate and having a stem slidably mounted in said stem aperture, said head comprising baked resin bonded sand.

5. In a mold, the combination of a cope and drag defining a casting cavity, said cope having an opening communicating with said cavity, a porous head mounted in and spaced from the bottom of said opening and formed with an axial stopper stem aperture, said drag having a gate formed with a seat coaxial with said aperture, a stopper engageable with said seat to close said gate and having a stem slidably mounted in said stem aperture, said head comprising baked resin bonded sand, a chill washer engaged against the lower surface of said head to slidably receive and guide said stopper stem and to prevent a flow of molten metal upwardly through the stem aperture in said head.

6. In a mold, the combination of a cope and drag defining a casting cavity, said cope having an opening communicating with said cavity, a porous head mounted in and spaced from the bottom of said opening and formed with an axial stopper stern aperture, said drag having a gate formed with a seat coaxial with said aperture, a stopper engageable with said seat to close said gate and having a stem slidably mounted in said stern aperture, said head comprising baked resin bonded sand, a chill washer engaged against the lower surface of said head to slidably receive and guide said stopper stem and to prevent a flow of molten metal upwardly through the stem aperture in said head, the marginal portion of said washer being imbedded in said head.

7. In a mold, the combination of a cope and drag defining a casting cavity, said cope having an opening communicating with said cavity, a porous head mounted in and spaced from the bottom of said opening and formed with an axial stopper stem aperture, said drag having a gate formed with a seat coaxial with said aperture, a stopper engageable with said seat to close said gate and having a stem slidably mounted in said stern aperture, said head comprising baked resin bonded sand, said cope having an annular downwardly facing shoulder to engage said head against upward movement out of said opening when the head is engaged by molten metal within the mold.

8. In a mold, the combination of a cope and drag defining a casting cavity, said cope having an opening communicating with said cavity, a porous head mounted in and spaced from the bottom of said opening and formed with an axial stopper stem aperture, said drag having a gate formed with a seat coaxial with said aperture, a stopper engageable with said seat to close said gate and having a stem slidably mounted in said stem aperture, said head comprising baked resin bonded sand, a metallic washer engaged against the lower surface of said head to slidably receive and guide said stopper stem and to prevent a flow of molten metal upwardly through the stem aperture in said head, a guide structure mounted on said cope and coacting with said washer to guide said stopper stem.

9. In a mold, the combination of a cope and drag defining a casting cavity, said cope having an opening communicating with said cavity, a porous head mounted in and spaced from the bottom of said opening and formed with an axial stopper stern aperture, said drag having a gate formed with a seat coaxial with said aperture, a stopper engageable with said seat to close said gate and having a stem slidably mounted in said stem aperture, said head comprising baked resin bonded sand, a guide washer engaged against the lower surface of said head to slidably receive and guide said stopper stem and to prevent a flow of molten metal upwardly through the stem aperture in said head, a guide structure mounted on said cope and coacting with said washer to guide said stopper stem, said guide structure including a flexible tube detachably mounted on a guide ring to slidably receive said stopper stem, and means to secure said tube and stem against relative movement.

10. In a mold, the combination of a cope and drag defining a casting cavity, said cope having an opening communicating with said cavity, a porous head mounted in said opening and formed with an axial stopper stem aperture, said drag having a gate formed with a seat coaxial with said aperture, and a stopper engageable with said seat to close said gate and having a stem slidably mounted in said stem aperture.

11. In a mold, the combination of a cope and drag defining a casting cavity, said cope having an opening communicating with said cavity, a porous head mounted in said opening and formed with an axial stopper stem aperture, said drag having a gate formed with a seat coaxial with said aperture, a stopper engageable with said seat to close said gate and having a stem slidably mounted in said stem aperture, and means on the cope and head for positively stopping upward movement of the latter during pouring of said mold.

12. In a mold, cope having a porous riser sand dome formed with an opening to receive a stopper stem, a guide washer mounted on the lower surface of said sand dome to snugly slidably receive and guide the stopper stem, the marginal portion only of said washer being imbedded in the sand dome, a guide structure mounted on said cope above said sand dome to slidably receive said stopper stem.

13. In a mold, a cope having a porous riser sand dome formed with an opening to receive a stopper stem, a guide washer mounted on the lower surface of said sand dome to snugly slidably receive and guide the stopper stem, the marginal portion only of said washer being imbedded in the sand dome, a guide structure mounted on said cope above said sand dome to slidably receive said stopper stem, and means associated with said guide structure to engage and resist downward movement of said stem.

14. In a mold, a cope having a porous riser sand dome formed with an opening to receive a stopper stem, a guide washer mounted on the lower surface of said sand dome to snugly slidably receive and guide the stopper stem, the marginal portion only of said washer being imbedded in the sand dome, a guide structure mounted on said cope above said sand dome to slidably receive said stopper stern, and means assocaited with said guide structure to engage said stern against downward movement, said means including a tube, and clamp means to compress said tube against said stem.

References Cited in the file of this patent UNITED STATES PATENTS 486,327 Cushing et al Nov. 15, 1892 695,091 Clark et a1. Mar. 11, 1902 1,161,034 Davis Nov. 23, 1915 2,431,879 Mebs Dec. 2, 1947 2,459,025 Graham Jan. 11, 1949 2,659,944 Valyi Nov. 24, 1953 2,728,963 Rynerson et a1 Jan. 3, 1956 2,765,505 Sylvester Oct. 9, 1956 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,838,816 June 17, 1958 Charles F.. Strom It is herebfi certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 35, after hub" insert riser passage disposed above andpreferab'ly coaxial 'with'the hub column 4, line 3 after "in" insert and column 5 line 25 before "cope insert a column 6, line 17, for "assocaited" read associated Signed and sealed this 21st day of October 1958.

SEAL) ttest:

KARL MINE ROBERT c. WATSON Attesting Oflicer Commissioner of Patents 

